Pseudoscience and the Paranormal

astrologers claim, each planet has an influence on human behavior, even a small one, and if that influence varies according to where the planet is located, then predictions of at least the existence of the new planets should have been made long ago. But one will search the writings of Ptolemy and later astrologers in vain for any hint of such a prediction.

Goodman (1968) explains astrology’s failure to note the influences of the three “new” planets before their discovery by saying that a planet doesn’t have any astrological influence until it is discovered!

Astrologers are now claiming that there are more than nine planets in the solar system, apparently not wanting to be left out in the cold again should an additional planet be discovered. A favorite of astrologers is a planet called Vulcan that is said to orbit the Sun inside the orbit of Mercury. In 1968 Goodman said of this planet, “It’s important to mention here the still unseen planet Vulcan, the true ruler of Virgo, since its discovery is said to be imminent…. Many astrologers feel that Vulcan, the planet of thunder, will become visible through telescopes in a few years” (p. 203). Well, more than a few years have passed, and no one has yet seen Vulcan.

Actually, the idea of Vulcan is an old one that astrologers latched onto long after it was abandoned by the astronomers who first proposed that such a planet might exist. Vulcan was proposed to account for deviations in the orbit of Mercury, using the same logic that led Adams and Leverrier to hypothesize the existence of Neptune. In fact, it was Leverrier who in 1859 published a prediction about where Vulcan would be found. In the next few years sightings of the planet were made, but these were due to “hoaxes or wishful thinking at the telescope” (Culver and Ianna 1984, p. 164) and could not be confirmed. It is another important characteristic of science that incorrect predictions are recognized as such and dropped; astronomers wasted no further effort on Vulcan after it had been shown not to exist. The deviations in Mercury’s orbit turned out not to be due to the effects of a planet, but are explained by the General Theory of Relativity. The fascinating story of the search for Vulcan, the erroneous sightings of the planet and the final resolution of the deviation of Mercury’s orbit by Einstein is told by Baum and Sheehan in their excellent In Search of Planet Vulcan (1997).

Before moving on to a discussion of the studies that have examined the claims of astrologers, one additional theoretical problem of major proportions has to be discussed: the mechanism by which any alleged astrological influence would occur. In other words, how would the stars and planets make their influence felt? Several answers to this question have been proposed: gravity, tidal or electromagnetic forces, magnetic fields, or emission of some sort of particles.

Culver and Ianna (1984) have discussed the fatal weaknesses of all these hypothesized mechanisms for astrological influence. Basically, all the proposed forces or fields are far too weak to have any influence on human infants, let alone the massive influence that is required by astrology. The effects of gravity, for instance, decrease as the square of the distance between two objects. If planet A is twice as far from planet B as it is from planet C, the gravitational effect of A on B will be four times (2² = 4) less than the gravitational effect of A on C. The practical import of this is that the gravitational effects of the stars and planets on a newborn are essentially nonexistent. A mother holding her infant in her arms exerts a gravitational influence on the child that is twenty times greater than the gravitational influence of the planet Mars. Mars is much more massive than the mother, but it is also a great deal farther away from the child.

The case is even worse for tidal forces. These decrease as the cube of the distance between two objects. In the example above, the tidal forces of planet A on planet B are eight times less (2³ = 8) than the tidal forces of A on C. This means that, when one takes into account the other factors that go into the equation used to calculate tidal forces, the mother’s tidal influence on the child is 11 trillion times greater than that of the planet Mars.

Electromagnetic and magnetic forces are equally unlikely to be the influence astrology requires. Electromagnetic forces are well understood, and they are not responsible for astrological influence. Magnetic fields certainly exist, but some planets of great importance in astrology don’t have any. For example, the Moon, Venus, and Mars are devoid of such fields (Culver and lanna, 1984). As for emitted particles, Culver and Ianna point out that in the solar system only the Sun emits particles; the planets do not. Other stars also emit particles, but by the time they reach Earth they are so diffuse that they cannot influence individuals in the way that astrology requires.

Note also that astrology does not take into account any physical characteristics of the planets or stars. Their astrological influences are independent of size, mass, shape, temperature, age, composition, distance, and rotation. This disregard of physical characteristics is just what would be expected from a system based on magic, but not from a scientific system.

TESTING ASTROLOGICAL PREDICTIONS

In spite of the historical, logical, and theoretical shortcomings of astrology, it is still important to ask the purely empirical question, Does astrology work? That is, can it make predictions about, for example, personality, personal destiny, mate selection, or sex life? Many studies aimed at answering this question have been conducted; they are summarized and described in detail in Culver and Ianna (1984), Jerome (1977), Gauquelin (1979), Dean (1977), and Eysenck and Nias (1982). The treatment in these sources is more thorough than is possible here. The Dean volume, for example, contains nearly six hundred pages, all devoted to studies of astrological and related influences.

Before discussing studies of astrological predictions, it is necessary to review some elementary statistical concepts. This will be done in the context of an actual astrological prediction. This discussion will be vital not only in the present context but also in succeeding chapters where statistical tests are employed to evaluate pseudoscientific claims of various sorts.

According to astrologers, the most important astrological influence on personality is the sun sign (Dean 1977), the sign of the zodiac in which the Sun is located on the day of one’s birth. Linda Goodman (1971) claims that “an individual’s sun sign will be approximately 80 percent accurate” as a description of personality (p. xvi). There are hundreds of ways of classifying human personality, but one common method is to dichotomize personality types and then assign individuals to one or the other type. While this is a gross oversimplification, it is popular with many psychologists. One of the most popular ways of dichotomizing personality is into extroverts and introverts (Morris, 1979). The characteristic personality of the extrovert seems to be nicely defined by the typical description of Aries: bold, assertive, aggressive, self-confident, and determined (Dean 1977; Eysenck and Nias 1982). An obvious astrological prediction, then, is that more extroverts than introverts should be born under Aries. If there are no astrological influences on personality, then the number of extroverts and introverts born under Aries should be about the same (that word about is the source of much trouble and the reason why statistical analyses are so necessary).

To find subjects for our study, we advertise in a campus newspaper for individuals born between March 21 and April 19; thirty-two respond, and each is given a reliable and valid test of introversion and extroversion. To test the astrological prediction made above, all we have to do is count up the number of each personality type born under Aries. What if we find that sixteen extroverts and sixteen introverts were born under Aries? Clearly, such a finding offers no support for astrological theory. What if we find that thirty-two extroverts but no introverts were born under Aries? This result would support astrological theory and one would not need to do fancy statistical analysis to know that. But what if we find that seventeen extroverts and fifteen introverts were born under Aries? The difference is in the direction predicted by astrology, but is very small. It would be reasonable to attribute the result to chance—that is, the effect is not really due to astrological influences, but just to random “noise” in the data. What if twenty extroverts and twelve introverts are found to be born under Aries? Is this difference due to chance or to some nonchance factor such as astrological influence? In this example it would be difficult to tell just by looking at the data. Some people might be willing to accept the results as indicative of astrological influence, while others might say it was due merely to chance factors. Without some objective way of quantifying the effect of chance, there is no way to settle the argument. Statistical analysis provides such quantification and allows a precise statement of how likely a particular result is to have occurred by chance as opposed to being the result of nonchance factors.

It is agreed upon in all the sciences that if a statistical analysis shows that a particular result would have occurred by chance fewer than 5 times out of 100 (less than 5 percent of the time, or 1 time in 20) the result is